Low rates of apomixis and polyploidy in progeny of Thuringian Sorbus subgenus Tormaria

Abstract Triassic limestone areas of Thuringia are well-known for their richness hybrids between S. aria and torminalis (subgenus Tormaria ). Those have been originally described as endemic taxa (i.e. Sorbus heilingensis, isenacensis However, the former endemics recently synonymized with S . × decipiens ( Karpatiosorbus hybrida (Bechst.) Sennikov & Kurtto) due to diploidy putative sexuality. Generally, crosses diploid sexual parents should segregate intermediates well morphotypes close be outcome. To test clonality versus segregation, we investigated progeny 10 mother trees, derived from open pollination. Three ten seedlings each tree were cultivated, six leaf characters measured being indicative subgenus Aria , Torminalis For genetic characterization, used three ISSR microsatellite markers one chloroplast marker. The nine trees segregated; genome prevailed in pollen clouds. One polyploid tree, however, produced partly clonal proved facultative apomictic. This means that Thuringian polyploidization occurs at low rates starting hybrids. Exact comparisons geno- phenotypes a frequent uncoupling genes responsible morphology, pointing excessive genomic rearrangement within trees. Only 1/3 -genotypes possessed -phenotype. Most them belong forma incisa, type slightly incise leaves. plasticity parental species may explained by introgression torminalis.